Efficacy of postexposure treatment with chimeric anti-PA monoclonal antibody (cAb29). Rabbits (n = 12) were exposed i.n. to Vollum spores and at 24 h postinfection were treated i.v. with 1 mg/ml of the cAb29 antibodies. Upper panel, treatment efficacy relative to the bacteremia at treatment initiation; lower panel, survival curves of the nonbacteremic (blue), bacteremic (red), and untreated (dashed black) rabbits. α, anti-.